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Development and Evaluation of a Novel VHH-Based Immunocapture Assay for High-Sensitivity Detection of Shiga Toxin Type 2 (Stx2) in Stool Samples. J Clin Microbiol 2020; 58:JCM.01566-19. [PMID: 31826960 DOI: 10.1128/jcm.01566-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/04/2019] [Indexed: 12/16/2022] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) is the main cause of postdiarrheal hemolytic-uremic syndrome (HUS), a life-threatening clinical complication characterized by hemolytic anemia, thrombocytopenia, and acute renal failure that mainly affects children. A relevant feature of STEC strains is the production of Stx, and all of them express Stx1 and/or Stx2 regardless of the strain serotype. Therefore, Stx detection assays are considered the most suitable methods for the early detection of STEC infections. Single-domain antibodies from camelids (VHHs) exhibit several advantages in comparison with conventional antibodies, making them promising tools for diagnosis. In this work, we have exploited VHH technology for the development of an immunocapture assay for Stx2 detection. Thirteen anti-Stx2 VHHs previously obtained from a variable-domain repertoire library were selected and evaluated in 130 capture-detection pair combinations for Stx detection. Based on this analysis, two VHHs were selected and a double VHH-based biotin-streptavidin capture enzyme-linked immunosorbent assay (ELISA) with spectrophotometric detection was developed and optimized for Stx2 detection. This assay showed an excellent analytical and clinical sensitivity in both STEC culture supernatants and stool samples even higher than the sensitivity of a commercial ELISA. Furthermore, based on the analysis of stool samples, the VHH-based ELISA showed high correlation with stx 2 detection by PCR and a commercial rapid membrane-based immunoassay. The intrinsic properties of VHHs (high target affinity and specificity, stability, and ease of expression at high yields in recombinant bacteria) and their optimal performance for Stx detection make them attractive tools for the diagnosis of HUS related to STEC (STEC-HUS).
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Cheong HI, Jo SK, Yoon SS, Cho H, Kim JS, Kim YO, Koo JR, Park Y, Park YS, Shin JI, Yoo KH, Oh D. Clinical Practice Guidelines for the Management of Atypical Hemolytic Uremic Syndrome in Korea. J Korean Med Sci 2016; 31:1516-28. [PMID: 27550478 PMCID: PMC4999392 DOI: 10.3346/jkms.2016.31.10.1516] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/10/2016] [Indexed: 12/19/2022] Open
Abstract
Atypical hemolytic uremic syndrome (aHUS) is a rare syndrome characterized by micro-angiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The major pathogenesis of aHUS involves dysregulation of the complement system. Eculizumab, which blocks complement C5 activation, has recently been proven as an effective agent. Delayed diagnosis and treatment of aHUS can cause death or end-stage renal disease. Therefore, a diagnosis that differentiates aHUS from other forms of thrombotic microangiopathy is very important for appropriate management. These guidelines aim to offer recommendations for the diagnosis and treatment of patients with aHUS in Korea. The guidelines have largely been adopted from the current guidelines due to the lack of evidence concerning the Korean population.
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Affiliation(s)
- Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
- Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea
| | - Sang Kyung Jo
- Division of Nephrology, Department of Internal Medicine, Korea University School of Medicine, Seoul, Korea
| | - Sung Soo Yoon
- Department of Internal Medicine, Seoul National University, Seoul, Korea
| | - Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jin Seok Kim
- Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Severance Hospital, Seoul, Korea
| | - Young Ok Kim
- Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea
| | - Ja Ryong Koo
- Division of Nephrology, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Korea
| | - Yong Park
- Division of Hematology, Department of Internal Medicine, Korea University School of Medicine, Seoul, Korea
| | - Young Seo Park
- Department of Pediatrics, Asan Medical Center Children's Hospital, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae Il Shin
- Department of Pediatrics, Severance Children's Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Kee Hwan Yoo
- Department of Pediatrics, Korea University Guro Hospital, Seoul, Korea
| | - Doyeun Oh
- Department of Internal Medicine, School of Medicine, CHA University, Seongnam, Korea.
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Abstract
Salmonella, Shigella, and Yersinia cause a well-characterized spectrum of disease in humans, ranging from asymptomatic carriage to hemorrhagic colitis and fatal typhoidal fever. These pathogens are responsible for millions of cases of food-borne illness in the United States each year, with substantial costs measured in hospitalizations and lost productivity. In the developing world, illness caused by these pathogens is not only more prevalent but also associated with a greater case-fatality rate. Classic methods for identification rely on selective media and serology, but newer methods based on mass spectrometry and polymerase chain reaction show great promise for routine clinical testing.
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Abstract
Shiga toxin-producing Escherichia coli (STEC) is among the common causes of foodborne gastroenteritis. STEC is defined by the production of specific toxins, but within this pathotype there is a diverse group of organisms. This diversity has important consequences for understanding the pathogenesis of the organism, as well as for selecting the optimum strategy for diagnostic testing in the clinical laboratory. This review includes discussions of the mechanisms of pathogenesis, the range of manifestations of infection, and the several different methods of laboratory detection of Shiga toxin-producing E coli.
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Shiga toxin-producing Escherichia coli: a single-center, 11-year pediatric experience. J Clin Microbiol 2014; 52:3647-53. [PMID: 25078916 DOI: 10.1128/jcm.01231-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to identify the best practices for the detection of Shiga toxin-producing Escherichia coli (STEC) in children with diarrheal illness treated at a tertiary care center, i.e., sorbitol-MacConkey (SMAC) agar culture, enzyme immunoassay (EIA) for Shiga toxin, or the simultaneous use of both methods. STEC was detected in 100 of 14,997 stool specimens submitted for enteric culture (0.7%), with 65 cases of E. coli O157. Among E. coli O157 isolates, 57 (88%) were identified by both SMAC agar culture and EIA, 6 (9%) by SMAC agar culture alone, and 2 (3%) by EIA alone. Of the 62 individuals with diarrheal hemolytic uremic syndrome (HUS) seen at our institution during the study period, 16 (26%) had STEC isolated from cultures at our institution and 15 (24%) had STEC isolated at other institutions. No STEC was recovered in 31 cases (50%). Of the HUS cases in which STEC was isolated, 28 (90%) were attributable to E. coli O157 and 3 (10%) were attributable to non-O157 STEC. Consistent with previous studies, we have determined that a subset of E. coli O157 infections will not be detected if an agar-based method is excluded from the enteric culture workup; this has both clinical and public health implications. The best practice would be concomitant use of an agar-based method and a Shiga toxin EIA, but a Shiga toxin EIA should not be considered to be an adequate stand-alone test for detection of E. coli O157 in clinical samples.
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A sensitive multiplex, real-time PCR assay for prospective detection of Shiga toxin-producing Escherichia coli from stool samples reveals similar incidences but variable severities of non-O157 and O157 infections in northern California. J Clin Microbiol 2013; 51:3000-5. [PMID: 23843484 DOI: 10.1128/jcm.00991-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rapid and accurate detection of Shiga toxin-producing Escherichia coli (STEC) of all serotypes from patients with diarrhea is critical for medical management and for the prevention of ongoing transmission. In this prospective study, we assessed the performance of a multiplex, real-time PCR assay targeting stx1 and stx2 for the detection of O157 and non-O157 STEC in diarrheal stool samples enriched in Gram-negative broth. We show that the assay is 100% sensitive (95% confidence interval [CI], 89.1% to 100%) and 98.5% specific (95% CI, 90.6% to 99.9%) based on a panel of 40 known STEC-positive specimens and 65 known negative specimens. During a 2-year postvalidation period, the assay detected more positive samples from patients in northern California than did culture and PCR testing performed at a public health reference laboratory, with a positive predictive value of 95.6% (95% CI, 87.6% to 99.1%). Serotyping data showed an incidence rate of 51.2% for non-O157 STEC strains, with 5.8% of patients (1/17) with non-O157 strains and 42.9% (6/14) with O157 strains (P = 0.03) developing hemolytic-uremic syndrome. The findings from this study underscore the recommendations of the CDC for laboratories to test all diarrheal stool samples from patients with acute community-acquired diarrhea for non-O157 STEC in addition to the O157 serotype by using a sensitive assay. Additionally, a survey of 17 clinical laboratories in northern California demonstrated that nearly 50% did not screen all stool specimens for the presence of Shiga toxins, indicating that many clinical microbiology laboratories still do not routinely screen all stool specimens for the presence of Shiga toxins as recommended in the 2009 CDC guidelines.
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Cronquist AB, Mody RK, Atkinson R, Besser J, Tobin D'Angelo M, Hurd S, Robinson T, Nicholson C, Mahon BE. Impacts of culture-independent diagnostic practices on public health surveillance for bacterial enteric pathogens. Clin Infect Dis 2012; 54 Suppl 5:S432-9. [PMID: 22572666 DOI: 10.1093/cid/cis267] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
For decades, culture has been the mainstay of diagnostic testing for bacterial enteric pathogens. This paradigm is changing as clinical laboratories adopt culture-independent methods, such as antigen-based tests and nucleic acid-based assays. Public health surveillance for enteric infections addresses 4 interrelated but distinct objectives: case investigation for localized disease control; assessment of disease burden and trends to prioritize and assess impact of population-based control measures; outbreak detection; and microbiologic characterization to improve understanding of pathogens, their virulence mechanisms, and epidemiology. We summarize the challenges and opportunities that culture-independent tests present and suggest strategies, such as validation studies and development of culture-independent tests compatible with subtyping, that could be adopted to ensure that surveillance remains robust. Many of these approaches will require time and resources to implement, but they will be necessary to maintain a strong surveillance system. Public health practitioners must clearly explain the value of surveillance, especially how outbreak detection benefits the public, and collaborate with all stakeholders to develop solutions.
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Affiliation(s)
- Alicia B Cronquist
- Disease Control and Environmental Epidemiology Division, Colorado Department of Public Health and Environment, 4300 Cherry Creek Dr S, Denver, CO 80426, USA.
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Gould LH. Update: Recommendations for Diagnosis of Shiga Toxin-Producing Escherichia coli Infections by Clinical Laboratories. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.clinmicnews.2012.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Point: Should all stools be screened for Shiga toxin-producing Escherichia coli? J Clin Microbiol 2011; 49:2390-4. [PMID: 21543568 DOI: 10.1128/jcm.00817-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In October 2009, the Centers for Disease Control and Prevention recommended that clinical laboratories test all stools submitted for the detection of enteric bacterial pathogens for the presence of Shiga toxin-producing Escherichia coli (STEC). In order to do this, it is recommended that all stools be cultured for Escherichia coli O157:H7 on selective medium as well as that testing for the presence of Shiga toxin be done by immunoassay to detect non-O157 STEC (3). There are a variety of products that are FDA approved for detection of Shiga toxin. Further, it is recommended that Shiga toxin detection be done by testing overnight enrichment broth cultures of stools rather than directly examining stools for this toxin. This recommendation was made approximately 18 months ago. We have asked Mario Marcon of Nationwide's Children Hospital in Columbus, OH, to explain the rationale for his decision to follow this recommendation, while we have asked Deanna Kiska and Scott Riddell of Upstate University Hospital in Syracuse, NY, why these guidelines have not been adopted by their laboratory.
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Fagerquist CK, Sultan O. Induction and identification of disulfide-intact and disulfide-reduced β-subunit of Shiga toxin 2 from Escherichia coli O157:H7 using MALDI-TOF-TOF-MS/MS and top-down proteomics. Analyst 2011; 136:1739-46. [PMID: 21336382 DOI: 10.1039/c0an00909a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The disulfide-intact and disulfide-reduced β-subunit of Shiga toxin 2 (β-Stx2) from Escherichia coli O157:H7 (strain EDL933) has been identified by matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomic analysis using software developed in-house. E. coli O157:H7 was induced to express Stx2 by culturing on solid agar media supplemented with 10-50 ng mL(-1) of ciprofloxacin (CP). Bacterial cell lysates at each CP concentration were analyzed by MALDI-TOF-MS. A prominent ion at mass-to-charge (m/z) ~7820 was observed for the CP concentration range: 10-50 ng mL(-1), reaching a maximum signal intensity at 20 ng mL(-1). Complex MS/MS data were obtained of the ion at m/z ~7820 by post-source decay resulting in top-down proteomic identification as the mature, signal peptide-removed, disulfide-intact β-Stx2. Eight fragment ion triplets (each spaced Δm/z ~33 apart) were also observed resulting from backbone cleavage between the two cysteine residues (that form the intra-molecular disulfide bond) and symmetric and asymmetric cleavage of the disulfide bond. The middle fragment ion of each triplet, from symmetric disulfide bond cleavage, was matched to an in silico fragment ion formed from cleavage of the backbone at a site adjacent to an aspartic acid or glutamic acid residue. The flanking fragment ions of each triplet, from asymmetric disulfide bond cleavage, were not matched because their corresponding in silico fragment ions are not represented in the database. Easier to interpret MS/MS data were obtained for the disulfide-reduced β-Stx2 which resulted in an improved top-down identification.
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Affiliation(s)
- Clifton K Fagerquist
- Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, CA 94710, USA.
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Top-down proteomic identification of furin-cleaved α-subunit of Shiga toxin 2 from Escherichia coli O157:H7 using MALDI-TOF-TOF-MS/MS. J Biomed Biotechnol 2011; 2010:123460. [PMID: 21331368 PMCID: PMC3038467 DOI: 10.1155/2010/123460] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 12/17/2010] [Indexed: 01/12/2023] Open
Abstract
A method has been developed to identify the α-subunit of Shiga toxin 2 (α-Stx2) from Escherichia coli O157:H7 using matrix-assisted laser desorption/ionization time-of-flight-time-of-flight tandem mass spectrometry (MALDI-TOF-TOF-MS/MS) and top-down proteomics using web-based software developed in-house. Expression of Stx2 was induced by culturing E. coli O157:H7 on solid agar supplemented with an antibiotic that elicits the bacterial SOS-response. Bacterial cell lysates were incubated in the presence of furin, a human enzyme, that cleaves α-Stx2 into A1 (~28 kDa) and A2 (~5 kDa) protein fragments. A subsequent disulfide reduction step unlinked A1 from A2. MALDI-TOF-MS of the furin-digested/disulfide-reduced sample showed a peak at mass-to-charge (m/z) 5286 that corresponded to the A2 fragment. No peak was observed that corresponded to the A1 fragment although its presence was confirmed by bottom-up proteomics. The peak at m/z 5286 was definitively identified by MALDI-TOF-TOF-MS/MS and top-down proteomics as the A2 fragment of α-Stx2.
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Hoefer D, Hurd S, Medus C, Cronquist A, Hanna S, Hatch J, Hayes T, Larson K, Nicholson C, Wymore K, Tobin-D'Angelo M, Strockbine N, Snippes P, Atkinson R, Griffin PM, Gould LH. Laboratory practices for the identification of Shiga toxin-producing Escherichia coli in the United States, FoodNet sites, 2007. Foodborne Pathog Dis 2010; 8:555-60. [PMID: 21186994 DOI: 10.1089/fpd.2010.0764] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Clinical laboratory practices affect patient care and disease surveillance. It is recommended that laboratories routinely use both culture for Escherichia coli O157 and a method that detects Shiga toxins (Stx) to identify all Stx-producing E. coli (STEC) and that labs send broths or isolates to a public health laboratory. In 2007, we surveyed laboratories serving Foodborne Diseases Active Surveillance Network sites that performed on-site enteric disease diagnostic testing to determine their culture and nonculture-based testing practices for STEC identification. Our goals were to measure changes over time in laboratory practices and to compare reported practices with published recommendations. Overall, 89% of laboratories used only culture-based methods, 7% used only Stx enzyme immunoassay (EIA), and 4% used both Stx EIA and culture-based methods. Only 2% of laboratories reported simultaneous culture for O157 STEC and use of Stx EIA. The proportion that ever used Stx EIA increased from 6% in 2003 to 11% in 2007. The proportion that routinely tested all specimens with at least one method was 66% in 2003 versus 71% in 2007. Reference laboratories were less likely than others to test all specimens routinely by one or more of these methods (48% vs. 73%, p=0.03). As of 2007, most laboratories complied with recommendations for O157 STEC testing by culture but not with recommendations for detection of non-O157 STEC. The proportion of laboratories that culture stools for O157 STEC has changed little since 2003, whereas testing for Stx has increased.
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Affiliation(s)
- Dina Hoefer
- New York State Department of Health, Bureau of Communicable Disease Control, Albany, New York 12237, USA.
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Shiga toxin-producing Escherichia coli in children: diagnosis and clinical manifestations of O157:H7 and non-O157:H7 infection. J Clin Microbiol 2010; 49:955-9. [PMID: 21177902 DOI: 10.1128/jcm.02119-10] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC), a cause of food-borne colitis and hemolytic-uremic syndrome in children, can be serotype O157:H7 (O157) or other serotypes (non-O157). E. coli O157 can be detected by culture with sorbitol-MacConkey agar (SMAC), but non-O157 STEC cannot be detected with this medium. Both O157 and non-O157 STEC can be detected by immunoassay for Shiga toxins 1 and 2. The objectives of this study were first to compare the diagnostic utility of SMAC to that of the Premier EHEC enzyme immunoassay (Meridian Diagnostics) for detection of STEC in children and second to compare the clinical and laboratory characteristics of children with serotype O157:H7 STEC and non-O157:H7 STEC infections. Stool samples submitted for testing for STEC between April 2004 and September 2009 were tested by both SMAC culture and the Premier EHEC assay at Children's Hospital Boston. Samples positive by either test were sent for confirmatory testing and serotyping at the Hinton State Laboratory Institute (HSLI). Chart review was performed on children with confirmed STEC infection. Of 5,110 children tested for STEC, 50 (0.9%) had STEC infection confirmed by culture; 33 were O157:H7 and 17 were non-O157:H7. The Premier EHEC assay and SMAC culture detected 96.0% and 58.0% of culture-confirmed STEC isolates (any serotype), respectively, and 93.9% and 87.9% of STEC O157:H7 isolates, respectively. There were no significant differences in disease severity or laboratory manifestations of STEC infection between children with O157:H7 and those with non-O157 STEC. The Premier EHEC assay was significantly more sensitive than SMAC culture for diagnosis of STEC, and O157:H7 and non-O157:H7 STEC caused infections of similar severity in children.
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Crawford LC, Crawford ML, Moore SR. Hemolytic-uremic syndrome in a grandmother. Emerg Infect Dis 2010; 16:1792-5. [PMID: 21029548 DOI: 10.3201/eid1611.091464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Lane C Crawford
- Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Glatstein M, Miller E, Garcia-Bournissen F, Scolnik D. Timing and utility of ultrasound in diarrhea-associated hemolytic uremic syndrome: 7-year experience of a large tertiary care hospital. Clin Pediatr (Phila) 2010; 49:418-21. [PMID: 20075028 DOI: 10.1177/0009922809342582] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The authors reviewed the clinical, laboratory, and imaging data from cases of diarrhea-associated hemolytic uremic syndrome (HUS D+), diagnosed at our institution, from 2001 to 2008. The timing and utility of ultrasonographic features of HUS D+ were analyzed. The aim of the study was to determine factors that could aid in the early diagnosis of this disease. A total of 13 children with HUS D+ were identified out of 23 patients with HUS diagnosed during this time period. Evidence of Escherichia coli 0157:H7 was found in 9 cases (70%). Ultrasound studies were ordered in 10 patients (71%), all of which showed renal sonographic findings compatible with HUS. Ultrasound was performed at a mean of 13 days after onset of the diarrhea. Of note, 2 patients whose ultrasounds were performed at the beginning of their diarrheal illness manifested ultrasonographic features suggestive of HUS when there was only a mild increase in serum creatinine and no decrease in hemoglobin or platelets, suggesting that ultrasonography can identify renal involvement early in the course of the disease before other systemic signs appear. Early renal ultrasound may be a useful adjunct in the initial evaluation in children with bloody diarrhea. Evidence of increased renal echogenicity in a patient with bloody diarrhea could aid in early recognition of HUS when other diagnoses such as intussusceptions are being entertained, potentially allowing early intervention.
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Affiliation(s)
- Miguel Glatstein
- Department of Pediatric Emergency Medicine, the Hospital for Sick Children, Toronto, Ontario, Canada.
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Das SK, Das AR, Guha AK. Gold nanoparticles: microbial synthesis and application in water hygiene management. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8192-9. [PMID: 19425601 DOI: 10.1021/la900585p] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A green chemical method to synthesize nanogold-bioconjugate and its eco-friendly promising role to purify contaminated waters has been described. Gold nanoparticles of 10 nm average diameter are produced on the surface of Rhizopus oryzae , a fungal strain, by in situ reduction of chloroauric acid (HAuCl(4)). The nanogold-bioconjugate (NGBC) showed strong adsorption capacity toward different organophosphorous pesticides. The EDXA study confirms adsorption of pesticides on the conjugate material surface. Morphological changes of the NGBC material after adsorption of organophosphorous pesticides were detected by atomic force micrographs. NGBC shows high antimicrobial activity against several Gram-negative and Gram-positive pathogenic bacteria as well as the yeasts Saccharomyces cerevisiae and Candida albicans . The treatment of microbial cells with NGBC caused rupture of cell membrane as revealed in scanning electron and fluorescence micrographs. These unique characteristics of NGBC have been successfully utilized to obtain potable water free from pathogens and pesticides in a single operation.
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Affiliation(s)
- Sujoy K Das
- Department of Biological Chemistry, Indian Association for the Cultivation of Science, Kolkata, India.
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Rapid and sensitive detection of Shiga toxin-producing Escherichia coli from nonenriched stool specimens by real-time PCR in comparison to enzyme immunoassay and culture. J Clin Microbiol 2009; 47:2008-12. [PMID: 19439539 DOI: 10.1128/jcm.02013-08] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) bacteria are a frequent cause of food-borne gastroenteritis, hemorrhagic colitis, and hemolytic uremic syndrome. Because antimicrobial agents are generally contraindicated in patients infected with STEC, a sensitive and specific diagnostic test with rapid turnaround is essential. Current culture methods may fail to detect non-O157 STEC. We evaluated a Stx gene real-time PCR assay using hybridization probes and the LightCycler instrument with 204 prospectively collected stool specimens, which were also tested for Stx by enzyme immunoassay (EIA) (ProSpecT STEC; Remel, Lenexa, KS) and by culturing on chromogenic agar (Chromagar O157; BD BBL, Sparks, MD). In addition, 85 archived stool specimens previously tested for Stx (by EIA) and/or E. coli O157:H7 (by culture) were tested by PCR. Sample preparation for PCR included mixing the stool in sterile water and extraction of nucleic acid using the MagNA Pure LC instrument (Roche Diagnostics). The PCR assay had 100% sensitivity and specificity compared to EIA and culture for specimens collected prospectively (4 of 204 specimens were positive) and compared to culture and/or EIA for archival specimens (42 of 85 specimens were positive). Both the EIA and PCR produced positive results from a specimen containing an O103 serotype STEC in the prospective specimens, and the PCR test detected three positive specimens that contained nonviable STEC in the archived specimens. The PCR assay demonstrated 100% sensitivity and specificity compared to EIA and/or culture and more rapid turnaround than either EIA or culture.
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Willford J, Mills K, Goodridge LD. Evaluation of three commercially available enzyme-linked immunosorbent assay kits for detection of Shiga toxin. J Food Prot 2009; 72:741-7. [PMID: 19435221 DOI: 10.4315/0362-028x-72.4.741] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Three commercially available Shiga toxin (Stx) enzyme-linked immunosorbent assay (ELISA) kits were evaluated for their ability to detect Stx in pure cultures of Stx-producing Escherichia coli (specificity). The detection limits (sensitivity) of each ELISA kit were also evaluated. Seventy-eight Stx-producing E. coli (STEC) isolates that produced Stx1, Stx2, or Stx1 and Stx2 variants were examined in this study. The specificities of the tests were comparable, and the sensitivities of two of the tests (Premier EHEC and rBiopharm Ridascreen Verotoxin Enzyme Immunoassay) were within the same order of magnitude. The ProSpecT Shiga Toxin E. coli Microplate Assay was approximately 10-fold less sensitive. The inability of all three tests to detect the Stx2d and Stx2e variants indicated that some STEC strains may not be detected by Stx ELISA. The ability of the Premier EHEC ELISA to detect toxin in artificially inoculated bovine fecal samples (following enrichment) indicated that this kit may be used to screen cattle for the presence of Stx as an indicator of the presence of STEC. In particular, such a screening method could be useful during the summer, when the number of STEC-positive animals and the number of STEC that they shed increase.
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Affiliation(s)
- John Willford
- Department of Animal Science, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82071, USA
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Cohen NJ, Jones RC, Schermond JS, Gerber SI. Identifying Shiga toxin-producing Escherichia coli: results of a laboratory evaluation. Foodborne Pathog Dis 2008; 5:295-298; quiz 299-301. [PMID: 18564910 DOI: 10.1089/fpd.2007.0077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Laboratory procedures for identifying Escherichia coli O157 and other Shiga toxin-producing E. coli (STEC) strains vary considerably, causing concern that these infections may be underdiagnosed. E. coli O157 may be screened for by culture on sorbitol-containing selective media; however, no selective medium is available for isolation of non-O157 STEC. Shiga toxins may be detected using enzyme immunoassay or real-time polymerase chain reaction; however, the organism is not isolated for subsequent characterization. The Centers for Disease Control and Prevention (CDC) recommends using both routine bacterial culture on sorbitol-containing medium and an assay for Shiga toxins to identify STEC. An evaluation of laboratories revealed limited compliance with these recommendations. Enhancing laboratory procedures to comply with the CDC guidelines is essential for public health surveillance.
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Affiliation(s)
- Nicole J Cohen
- Chicago Department of Public Health, Chicago, Illinois 60666, USA.
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Schuurman T, Roovers A, van der Zwaluw WK, van Zwet AA, Sabbe LJM, Kooistra-Smid AMD, van Duynhoven YTHP. Evaluation of 5'-nuclease and hybridization probe assays for the detection of shiga toxin-producing Escherichia coli in human stools. J Microbiol Methods 2007; 70:406-15. [PMID: 17614150 DOI: 10.1016/j.mimet.2007.05.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 04/29/2007] [Accepted: 05/22/2007] [Indexed: 01/01/2023]
Abstract
5'-Nuclease and a hybridization probe assays for the detection of shiga toxin-producing Escherichia coli were validated with regard to selectivity, analytical sensitivity, reproducibility and clinical performance. Both assays were capable of detecting the classical stx(1) and stx(2) genes when challenged with reference strains of E. coli (n=40), although 1 to 4 minority sequence variants, whose clinical relevance is limited (stx(1c), stx(1d), and stx(2f)), were detected less efficiently or not at all by one or both assays. No cross reaction was observed for both assays with 37 strains representing other gastrointestinal pathogens, or normal gastrointestinal flora. Analytical sensitivity ranged from 3.07 to 3.52 log(10) and 3.42 to 4.63 log(10) CFU/g of stool for 5'-nuclease and hybridization probe assay, respectively. Reproducibility was high with coefficients of variation of </=5% for both inter- and intra-assay variation. Clinical performance was identical with a panel of archived positive specimens (n=19) and a prospective panel of stools associated with bloody diarrhea (n=115). In conclusion, both assays proved to be sensitive and reproducible.
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Affiliation(s)
- Tim Schuurman
- Department of Research and Development, Laboratory for Infectious Diseases, Groningen, The Netherlands
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Al-Gallas N, Bahri O, Aissa RB. Prevalence of Shiga Toxin-Producing Escherichia coli in a Diarrheagenic Tunisian Population, and the Report of Isolating STEC O157:H7 in Tunis. Curr Microbiol 2006; 53:483-90. [PMID: 17115105 DOI: 10.1007/s00284-006-0184-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2006] [Accepted: 05/19/2006] [Indexed: 10/23/2022]
Abstract
In Mellassine (a major city in the state of Tunis) and Ben Arous state (south east of Tunis), a total of 212 stool samples were collected from children and adults (symptomatic and asymptomatic groups) between November 2001 and November 2004. Three hundred and twenty-seven E. coli strains were isolated and studied, to look for shiga toxin-producing Escherichia coli (STEC) strains, which were further analysed to investigate and determine clonal relationship among Tunisian STEC strains isolated from different sources (diarrheal cases and food products). They were analysed to characterize their serotypes, virulence genes by PCR, cytotoxic effect on Vero cell, plasmid profiles, and pulsed-field gel electrophoresis (PFGE) patterns. Eleven isolates (10 nontypeable, one O157:H7) carried stx gene and shared Stx restriction fragment length polymorphism (RFLP) patterns (stx1 ( + ), stx2 ( + )). Seven of these strains were isolated from acute diarrheal cases, and four were isolated from a control group (among which the only isolated STEC O157:H7). Two of the STEC strains harboured both eae and ehxA genes. Analysis of the cytotoxic effect on Vero cells showed that a correlation exists between carrying stx1 ( + ), stx2 ( + ) genes and cytotoxicity. Also a correlation was noticed between STEC strains recovered from different sources regarding plasmid profiles and PFGE patterns. All stool samples positive for STEC were nonbloody. None of the STEC-positive patients developed severe diseases. These data demonstrate that although STEC is not a major cause of acute diarrhea in Tunis, it should not be overlooked. Measures should be taken to improve the detection and isolation of STEC from acute diarrheal cases as well as carriers.
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Affiliation(s)
- Nazek Al-Gallas
- Laboratoire de Contrôle des Eaux et Denrées Alimentaires, Institut Pasteur de Tunis, Tunis, Tunisia
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23
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Abstract
Acute infectious diarrhea is a yearly occurrence for most Americans, and is associated with 1 million hospitalizations and about 6000 deaths in the United States annually. Up to 80% of acute infectious diarrhea is caused by noroviruses, which produce a clinically mild illness with a predictable short course and good outcome that make laboratory testing and antimicrobial treatment unnecessary. Most diarrhea-causing bacteria and protozoa can cause a clinical illness "like norovirus"; when they do so in healthy adults neither specialized testing nor antimicrobials is required. The presence or absence of epidemiologic evidence (such as travel, hospitalization, antibiotic use, other exposures)and clinical evidence (such as diarrhea frequency and duration, severity of abdominal pain and fever, character of stool, presence of chronic illness or immune deficiency) can change the probability of "not norovirus" from as low as 8% to as high as 100%. Such probabilities guide the use of laboratory testing and antimicrobial therapy in patients who have acute infectious diarrhea.
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Affiliation(s)
- Richard Goodgame
- Department of Medicine, Baylor College of Medicine, 1 Baylor Plaza, Room 525-D, Houston, TX 77030, USA.
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Ecker DJ, Sampath R, Willett P, Wyatt JR, Samant V, Massire C, Hall TA, Hari K, McNeil JA, Büchen-Osmond C, Budowle B. The Microbial Rosetta Stone Database: a compilation of global and emerging infectious microorganisms and bioterrorist threat agents. BMC Microbiol 2005; 5:19. [PMID: 15850481 PMCID: PMC1127111 DOI: 10.1186/1471-2180-5-19] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Accepted: 04/25/2005] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Thousands of different microorganisms affect the health, safety, and economic stability of populations. Many different medical and governmental organizations have created lists of the pathogenic microorganisms relevant to their missions; however, the nomenclature for biological agents on these lists and pathogens described in the literature is inexact. This ambiguity can be a significant block to effective communication among the diverse communities that must deal with epidemics or bioterrorist attacks. RESULTS We have developed a database known as the Microbial Rosetta Stone. The database relates microorganism names, taxonomic classifications, diseases, specific detection and treatment protocols, and relevant literature. The database structure facilitates linkage to public genomic databases. This paper focuses on the information in the database for pathogens that impact global public health, emerging infectious organisms, and bioterrorist threat agents. CONCLUSION The Microbial Rosetta Stone is available at http://www.microbialrosettastone.com/. The database provides public access to up-to-date taxonomic classifications of organisms that cause human diseases, improves the consistency of nomenclature in disease reporting, and provides useful links between different public genomic and public health databases.
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Affiliation(s)
- David J Ecker
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Rangarajan Sampath
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Paul Willett
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | | | - Vivek Samant
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Christian Massire
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Thomas A Hall
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Kumar Hari
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - John A McNeil
- Ibis Therapeutics, a division of Isis Pharmaceuticals, 1891 Rutherford Rd., Carlsbad, CA 92008, USA
| | - Cornelia Büchen-Osmond
- International Committee on Taxonomy of Viruses, Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 West 168th Street, New York, NY 10032, USA
| | - Bruce Budowle
- Laboratory Division, Federal Bureau of Investigation, Washington, DC 20535, USA
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Klein EJ, Stapp JR, Neill MA, Besser JM, Osterholm MT, Tarr PI. Shiga toxin antigen detection should not replace sorbitol MacConkey agar screening of stool specimens. J Clin Microbiol 2004; 42:4416; author reply 4416-7. [PMID: 15365063 PMCID: PMC516334 DOI: 10.1128/jcm.42.9.4416-4417.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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